This application pertains to the art of indicators and, more particularly, to indicators for indicating overtravel of a piston in a cylinder. The invention is particularly applicable for use with pressure converters and will be particularly described with reference thereto. However, it will be appreciated that the invention has broader aspects and may be used for indicating overtravel of other devices.
Piston overtravel indicators of a known type include that disclosed in U.S. Pat. No. 3,997,887 issued Dec. 14, 1976, to Poynter. In an arrangement of this type, an elongated indicator rod extends through a hole in a cylinder end wall toward which a piston moves. The indicator rod has a normal armed position extending inwardly through the cylinder end wall and an operated position extending outwardly thereof. In the event of overtravel of the piston toward the cylinder end wall, the piston engages the indicator rod for extending same to its operated position. This causes the rod to operate a switch assembly which is separately mounted to the end wall. The use of a completely separate switch assembly is very expensive.
In another prior arrangement, an electrical circuit is connected for completion between the cylinder piston and the indicator rod. Therefore, overtravel of the piston for engaging the indicator rod completes a circuit to operate a visual or audible indicator. However, return of the piston to the overtravel position again opens the electric circuit. It would be desirable to have an indicator of the type described wherein the electric circuit would remain closed once the piston overtraveled until the defect causing the overtravel was corrected and the indicator rod would then be manually moved back to its armed position.